Outbreak of infection with high-level gentamicin-resistant Enterococcus faecalis (HLGRE) in a Norwegian hospital

OBJECTIVES

To examine and characterize a suspected outbreak of high-level gentamicin-resistant Enterococcus (HLGRE) infection.

METHODS

Eighty-nine patients with clinical infection diagnosed during hospital stay or within 30 days after discharge in the period from June 1995 to 31 December 1999 were included in the study. One control patient was assigned for each HLGRE patient according to localization in the hospital (same ward), time of admission (+/-3 months), and age (+/-10 years). Unadjusted risk analysis and multivariate logistic regression analysis were performed. Sixty-nine HLGRE strains were subjected to PCR amplification of the genes coding for aminoglycoside-3'-O-phosphoryltransferase-III (APH(3')-III) and aminoglycoside-6'-N-acetyltransferase/2"-O-phosphoryltransferase-III (AAC(6')/APH(2")).

RESULTS

The gene aacA/aphD, associated with HLGRE, was detected by PCR in all isolates, and the gene aphA3, associated with high-level streptomycin, kanamycin and amikacin resistance, was detected in 56 of the 69 isolates. None of the 69 isolates was resistant to glycopeptides or ampicillin. Resistance to ciprofloxacin was found in 57 (82.6%). Pulsed-field gel electrophoresis analysis revealed 12 different genotypes, among which two major clusters dominated.

CONCLUSIONS

Both clonal expansion and the emergence of unique strains contributed to the increased number of infections caused by HLGRE. Urinary catheterization, duration of hospital stay and antibiotic therapy were significant risk factors for HLGRE infection.

Predictive value of tumour cell proliferation in locally advanced breast cancer treated with neoadjuvant chemotherapy

We previously reported that defects in apoptotic pathways (mutations in the TP53 gene) predicted resistance to doxorubicin monotherapy. The aim of this study was to evaluate whether cell proliferation, as assessed by mitotic frequency and Ki-67 levels, may provide additional predictive information in the same tumours and to assess any potential correlations between these markers and mutations in the TP53 gene and erbB-2 overexpression. Surgical specimens were obtained from ninety locally advanced breast cancers before commencing primary chemotherapy consisting of weekly doxorubicin (14 mg/m2) for 16 weeks. 38% of the patients had a partial response (PR) to therapy, 52% had stable disease (SD) while 10% had progressive disease (PD). Univariate analysis showed a significant association between a high cell proliferation rate (expressed as a high mitotic frequency) and resistance to doxorubicin (P = 0.001). Further analyses revealed this association to be limited to the subgroup of tumour expressing wild-type TP53 (P = 0.016), and TP53 mutation status was the only factor predicting drug resistance in the multivariate analyses. The finding that a high mitotic frequency, as well as a high Ki-67 staining, correlated to TP53 mutations (P = 0.001 for both), suggests TP53 mutations are the key predictor of drug resistance, although cell proliferation may play an additional role in tumours harbouring wild-type TP53. Regarding overall (OS) and relapse-free survival (RFS), multivariate analyses (Cox' proportional hazards regression) revealed a high histological grade and negative oestrogen receptor (ER) status to be the variables that were most strongly related to breast cancer death (P = 0.001 and P = 0.001, respectively). A key reason for this difference with respect to the factors predicting chemotherapy resistance could be due to the adjuvant use of tamoxifen in all patients harbouring ER-positive tumours.

Long-term changes in adult asthma prevalence

There has been an increase in asthma prevalence among children. Little evidence is available regarding long-term changes in asthma prevalence in adults. Two cross-sectional studies were performed among adults aged 15-70 yrs in Oslo, Norway, in 1972 and again in 1998-1999 (n=39,998). A postal self-completed questionnaire was used. Exactly the same questions and survey methods were used in both studies. In 1998-1999, additional telephone follow-up was included for postal nonresponders. The crude prevalence of ever having had a doctor's diagnosis of asthma increased from 3.4 to 9.3%. The prevalence of wheezing increased from 17.8 to 25.8% and attacks of breathlessness from 12.6 to 16.7%. After controlling for smoking, the risk of asthma among those aged <40 yrs had tripled. The increase in asthma was 50% greater in females than males. The prevalence of symptoms increased less than asthma diagnosis. Wheezing increased by 50% in those aged <40 yrs, with smaller increases at greater ages. The increase in symptoms was seen among both asthmatics and nonasthmatics. There has been a large increase in the prevalence of asthma diagnosis and asthma-like symptoms in adults. The increase is less pronounced among those aged >40 yrs.

Tuberculin reactivity: prevalence and predictors in BCG-vaccinated young Norwegian adults

We studied tuberculin reactivity in young Norwegian adults and its possible dependency on age, gender, previous BCG vaccination, smoking habits, occupational exposure, diet as well as years of education as a measure of socio-economic status. Responders of a random sample of men and women aged 20-44 years living in Bergen, Norway were interviewed and tested withthe adrenaline-Pirquettest with Norwegian-produced synthetic mediumtuberculin at the out-patient chest clinic in the city of Bergen in 1992-1993. Nine hundred and three subjects out of 1200 met for the clinical examination (75%). Five hundred and eighty-eight subjects were tuberculin-tested and read, whereof 95% were BCG vaccinated by age 14. Mean tuberculin reactivity was 4.8 mm (SD: 3.0 mm). A positive reaction (> or = 4 mm) was found in 64%, whereof 7% had a strongly positive reaction (>10 mm). A negative reaction (<4 mm) occurred in 36%, whereof 10% had no reaction (0 mm). Only 30% ofthe females and 36% of the males aged 21--25 years were tuberculin positive 7-12 years after BCG vaccination. Linear regression analysis demonstrated tuberculin reactivity to increase with increasing age, male gender with an increasing sex effect by age, and current smoking. Occupational dust or gas exposure, a diet rich in vitamin C or years of education did not influence tuberculin reactivity significantly.

Incidence of asthma and respiratory symptoms by sex, age and smoking in a community study

The purpose of this study was to establish incidence rates for a wide range of respiratory symptoms and asthma, and relate them to sex, age, and smoking habits. A cohort established in 1985 as a random sample from the population of Western Norway, aged 15-70 yrs, was followed-up in 1996-1997. Of the initial cohort of 3,786 subjects, a total of 2,819 replied to mailed questionnaires at both baseline and follow-up. The 11-yrs cumulative incidence of asthma was 4.0% in males and 3.5% in females. For respiratory symptoms, the cumulative incidences for both sexes varied between 2.0% (dyspnoea grade 4) and 25.8% (wheezing), being higher in females than males for most symptoms. For calculation of odds ratios (ORs) multivariate logistic regression analyses were used. The sex and smoking-adjusted incidences increased by age for all symptoms except wheezing and attacks of dyspnoea. Those starting to smoke within the follow-up had ORs of 1.9-2.2 for the cough symptoms compared to never-smokers, after adjusting for sex, age, and pack-yrs. To conclude, the 11-yrs incidence of dyspnoea increased with increasing pack-yrs, after adjusting for sex, age, and changes in smoking habits. This indicated that when analysing other risk factors, adjustment has to be made for the risks posed by smoking, sex and age.

Absence of relationship between tuberculin reactivity and asthmatic symptoms, level of FEV1 and bronchial hyperresponsiveness in BCG vaccinated young adults

BACKGROUND

Some recent studies have suggested that bacillus Calmette-Guérin (BCG) vaccination or mycobacterial infection early in life is inversely related to asthma. We wondered if an increase in tuberculin reactivity was inversely related to commonly used indices of asthma in a population of young adults who were BCG vaccinated at age 14.

METHODS

Men and women aged 20-44 years, randomly selected from the general population, were tuberculin tested with the epinephrine-Pirquet method with Norwegian-produced synthetic medium tuberculin (n = 588). In addition they were interviewed using eight questions on asthma symptoms and medication. Lung function and bronchial responsiveness were also tested.

RESULTS

Altogether 95% of those studied had been BCG vaccinated at age 14 (n = 558). In the 386 subjects with complete examinations, there was no relationship between a positive tuberculin reaction (> or = 4 mm) and asthma symptoms or use of asthma medication. Furthermore we did not observe any relationship between a positive tuberculin reaction and the level of forced expiratory volume (FEV1) or a positive bronchial responsiveness test, assessed as the percent of predicted of FEV1 and PD20 < 2 mg methacholine, respectively. In multiple logistic regression analyses neither respiratory symptoms, level of FEV1, nor bronchial hyperresponsiveness were related to tuberculin reactivity after adjustment for age, gender and smoking habits.

CONCLUSIONS

In this young adult population who were BCG vaccinated at the age of 14 no significant relationship existed between tuberculin reactivity and asthmatic symptoms, level of FEV1 or bronchial hyperresponsiveness. Our data does not support the hypothesis that BCG immunization is beneficial in reducing asthmatic symptoms and disease in young adults.

Biometric measurements of the eyes in teenagers and young adults with Down syndrome

PURPOSE

To examine ocular biometric variables in subjects with Down syndrome.

METHODS

In a population-based study we have compared ocular biometric variables in a group of 47 individuals with Down syndrome (20.0+/-3.9 years) with 51 control subjects (21.0+/-4.6 years).

RESULTS

A thinner cornea (0.48+/-0.04 mm vs. 0.55+/-0.03 mm, p<0.001) and higher keratometry values (46.39+/-1.95 D vs. 43.41+/-1.40 D, p<0.001) were found in the Down syndrome group than in the control group. Oblique astigmatism was commonly found in the Down syndrome individuals, showing a strong right-left specificity (right eyes' axes in the 135 degrees -meridian, left eyes' axes in the 45 degrees -meridian). The lens was thinner (3.27+/-0.29 mm vs. 3.49+/-0.20 mm) and the calculated lens power was weaker (17.70+/-2.36 D vs. 19.48+/-1.24 D) in the Down syndrome group than in the control group (p<0.001 in both cases).

CONCLUSIONS

Thinning of the corneal stroma may account for the steeper cornea and the high frequency of astigmatism in Down syndrome due to lower corneal rigidity. It may also be of etiological importance to the increased incidence of keratoconus in Down syndrome.

Corneal grafting for keratoconus in mentally retarded patients

PURPOSE

To compare the results of penetrating and non-penetrating corneal grafting procedures in mentally retarded keratoconus patients.

METHODS

In the years 1974-2000 41 mentally retarded patients with keratoconus (33 with Down syndrome) were operated with corneal grafting. Mean age at operation was 36.7+/-10.8 years. Three different surgical procedures were used (no randomization): penetrating keratoplasty (n=16), lamellar keratoplasty (n=5) and epikeratophakia (n=20). In a retrospective study, the non-penetrating procedures (lamellar keratoplasty and epikeratophakia) were compared to the penetrating keratoplasties with regard to graft survival and frequency of serious complications. Mean follow-up time of all grafting procedures was 80+/-58 months.

RESULTS

All cases of serious complications (irreversible rejection, wound leakage or perforation) occurred in the penetrating keratoplasty group (p=0.0005). Older age at operation (p=0.011) adversely influenced the frequency of serious complications. Overall five-year survival was 74.9%. Graft survival was not related to surgical procedure, but rather to age at operation (poorer survival in older age, p=0.012) and degree of retardation (poorer survival in patients with more severe retardation, p=0.051).

CONCLUSIONS

Because of the safety and low frequency of complications, epikeratophakia is recommended as the grafting procedure of choice in the majority of mentally retarded with keratoconus. In selected cases (good cooperation, age < or =40 years, and a good peripheral corneal thickness) penetrating keratoplasty may be performed, which, if uncomplicated, often will give better functional/optical results.

Attributable fractions: fundamental concepts and their visualization

A general methodology for visualizing attributable fractions in epidemiology is described. The methodology applies to the multifactorial exposure situation and embraces various types of attributable fractions including adjusted, sequential and average attributable fractions. The concept of the scaled Venn diagram plays a central role, illustrating total disease risk and excess disease risk attributable to the exposures as areas in a unit square. This forms the ground for making simple pie charts of attributable fractions summing to 1 (or 100%). The potential applications extend from cohort and cross-sectional data to data from case-control studies. The methodology is illustrated by theoretical as well as empirical examples including the risk of motor fatalities attributable to driver's blood alcohol concentration and age, and the prevalence of chronic cough attributable to smoking habits, occupational exposure to dust or gas, and residence. A total of 40 figures illustrate the methodology.

Increased circulating levels of alpha1-antitrypsin and calprotectin are associated with reduced gas diffusion in the lungs

The aim was to examine the relationship of serum inflammatory markers to the level of single-breath diffusing capacity of carbon monoxide (TL,CO). A stratified sample (n = 1,121) of a Norwegian general population aged 18-73 yrs was examined. The inflammatory markers measured were calprotectin, a prominent protein in the cytosol fraction of neutrophil granulocytes, and alpha1-antitrypsin (alpha1-AT), the major inhibitor of neutrophil elastase in the lower respiratory system. Both markers have increased circulating levels in the course of an acute inflammatory reaction. Subjects with a TL,CO < 80% of predicted value had a higher level of both alpha1-AT (p = 0.003) and calprotectin (p < 0.03) than those with a TL,CO > 100%. In multiple linear regression analyses, alpha1-AT was still significantly associated with TL,CO after adjusting for sex, age, smoking habits, haemoglobin, carboxyhaemoglobin, forced expiratory volume in one second and alveolar volume. In a similar analysis, no significant overall association was found between calprotectin and TL,CO, but in a stratified analysis, calprotectin was significantly related to TL,CO in females. However, no significant sex interaction in the relationship between the inflammatory markers and TL,COo was found. The findings suggest that increased levels of alpha1-antitrypsin and of calprotectin are risk factors for decreased diffusing capacity of carbon monoxide.

Comparing the adrenaline-Pirquet test with international PPD tuberculin tests

Several tuberculins, strengths and setting methods are in everyday use. We wanted to compare the Norwegian reference adrenaline Pirquet test with the internationally recommended Mantoux PPD test and Rhoditest. In responders of a random sample of young adults, with randomization of test subjects, we intra-individually compared the adrenaline-Pirquet (aP) test with Norwegian-produced synthetic medium tuberculin (SMT) with either the Mantoux test with PPD 2 tuberculin units (TU) (M2), the Mantoux-PPD 5 TU (M5) or the PPD 2 TU-Rhoditest (Rh). The criteria for a positive reaction were > or = 4mm for the aP test, > or = 10 mm for the M2 test, > or = 6 mm for the M5 test and > or = 2 mm for the Rh test. Strongly positive reactions were defined as aP test > or = 10 mm and M2/M5 test > or = 15 mm. One of the tuberculin tests was positive while the comparison test was negative in 14% of the M2 test group (n = 236), 15% in the M5 test group (n = 162) and 20% in the Rh test group (n = 187). The three PPD tests had positive reactions 3-10 times as often, with a simultaneous negative aP test, than vice versa. Strongly positive reactions occurred in 7% of the aP tests (> or = 10 mm), 32% of the M2 tests (> or = 15 mm) and in 41% of the M5 tests (> or = 15 mm). Receiver operating characteristic (ROC) curves gave the best agreement, with aP test >3mm compared with the M2 and the Rh tests. Regression equations are presented for transformations of the Norwegian reference method of adrenaline-Pirquet results to internationally recommended PPD tests. The international recommendations, globalization in general and the skill of Norwegian public health nurses in performing intra-dermal BCG suggest a future shift to the PPD 2 TU Mantoux test in Norway. Due to the lack of sensitivity and specificity of all tuberculin tests they might be used in targeted tuberculin testing and not as a general screening procedure in a low-incidence tuberculosis area with BCG-vaccinated inhabitants.

Tunnel restorations placed in routine practice and observed for 24 to 54 months

OBJECTIVE

The purpose of this study was to evaluate the feasibility and performance of tunnel restorations placed in routine public dental service.

METHOD AND MATERIALS

A total of 420 small approximal lesions received tunnel restorations 12 general practitioners. Three hundred two restorations in 179 patients were available for evaluation after a minimum period of 24 months. The restorations were evaluated by modified US Public Health Service criteria.

RESULTS

After service periods up to 54 months, 57% of the restorations were found to be clinically and radiographically acceptable. The remainder had already been replaced or were assessed as unacceptable. High levels of carious activity and internal-type preparations resulted in the poorest prognosis. The success rates varied considerably among the operators, but these differences did not reach statistical significance.

CONCLUSION

The indications for use of the tunnel restoration technique for the treatment of primary approximal lesions seem to be limited at present. Partial tunnel restorations may have a somewhat better prognosis than the internal tunnels, but high carious activity has a detrimental effect. Tunnel restorations may be considered for particularly cooperative patients with a low caries rate as a semipermanent treatment for small lesions.

Nosocomial outbreak of ampicillin resistant Enterococcus faecium: risk factors for infection and fatal outcome

A nosocomial outbreak caused by ampicillin resistant Enterococcus faecium (ARE) was detected at a Norwegian university hospital in January 1995. Prior to this outbreak, ARE were not common in this hospital or other hospitals in Norway. During 1995 and 1996, a total of 149 cases with clinical ARE infection were detected prospectively. A case control study was performed by allocating controls matched for gender, age and ward of admission. Altogether, 123 case control pairs with mean age 70.1 years were included. Isolates from 89 (72. 4%) of the cases were identical or related to the defined outbreak strain as determined by pulsed-field gel electrophoresis (PFGE). In 75 of the patients (60.9%), ARE caused urinary tract infection, five (4.1%) had bacteraemia, 33 (26.8%) had wound infection and 10 (8.1%) had other infections. In a logistic regression model for 1:1 matched samples, the following factors were identified as significant risk factors for ARE infection: underlying neurological disease (OR=33.5), prescription of antimicrobial agents for more than 10 days (OR=8. 99), prescription of cephalosporins (OR=4.69), underlying gastrointestinal disease (OR=3.36) and length of hospital stay per day (OR=1.04). The intrahospital death rate for the cases was 18.7% compared with 8.9% for the controls, corresponding to an excess mortality attributable to ARE infection of 9.8%. A history of carbapenem prescription was the only independent factor contributing to death (OR=5.64) when comparing ARE patients dying in hospital to those surviving.

The single-breath transfer factor for carbon monoxide and respiratory symptoms in a Norwegian community sample

Reduced single-breath transfer factors of the lung for carbon monoxide are seen in a number of conditions. The hypothesis of the present study was that self-reported respiratory symptoms differ in their prediction of TL,CO level in a general population in Norway. A cross-sectional survey of a general population sample in Norway, made up of 1,275 subjects aged 18-73 yrs, was conducted in 1987-1988. The attendees (84% response rate) filled in a questionnaire on respiratory symptoms and underwent standardized spirometric and TL,CO measurements and clinical examination. Associations between TL,CO and respiratory symptoms were assessed using multiple regression models. Tests for interaction were used to examine whether these associations varied with sex, age and smoking habits. Data from 1,221 subjects were analysed. Both males and females who reported respiratory symptoms had significantly lower TL,CO after adjusting for age and height. In a multiple linear regression analysis of TL,CO, adjusting for sex, age, height and smoking habits, the symptoms for which statistical significance was attained, were morning cough, chronic cough and breathlessness. However, only the breathlessness score was independently associated with the TL,CO (-0.42 mmol x min(-1) x kPa(-1) per breathlessness score unit) after adjusting for other respiratory symptoms, and the relationship was stronger in males than in females. In this study, the strongest predictor for a decreased single-breath transfer factor of the lung for carbon monoxide was the presence of self-reported breathlessness, regardless of age, smoking habits and height.

Tuberculin test variability: using the Norwegian Adrenaline-Pirquet method

SETTING

Chest Unit, Bergen, Norway.

OBJECTIVES

To study the agreement between two Adrenaline-Pirquet tuberculin tests and compare reactivity in groups read after 2, 3 and 4 days.

DESIGN

Responders from a random sample of 1200 men and women 20-44 years of age in 1991 were tested with dual Adrenaline-Pirquet skin scratch tests with Norwegian-produced synthetic medium tuberculin and read after 2-7 days.

RESULTS

Of 588 subjects dually tuberculin tested, complete agreement existed in 220 (37.4%). A difference of 1 mm one way or the other was observed in 239 (40.6%), whereas a difference of less than 3 mm was found in 567 (96.5%). Using the larger of the two reactions increased the rate of tuberculin positivity (> or =4 mm) by up to 8.4% compared with reading only one of the tests. No statistically significant differences were observed between subjects whose reactions were read after 2, 3 and 4 days.

CONCLUSION

Under the non-blinded conditions of this study the dual Adrenaline-Pirquet tuberculin tests demonstrated reproducibility equivalent to the internationally recommended Mantoux test, and appeared to be independent of time of reading within four days.

Applicability of the single-breath carbon monoxide diffusing capacity in a Norwegian Community Study

The test of single-breath diffusing capacity for carbon monoxide (DLCO) has been widely used in population surveys. However, little is known about the effect of meeting or failing to meet the criteria for acceptability of this test. The American Thoracic Society (ATS) recommends a breathholding time of 9 to 11 s, two measurements within +/- 10% or 3 ml CO(STPD)/min/mm Hg of the average DLCO, and an inspiratory vital capacity (IVC) of at least 90% of the largest previously measured forced vital capacity (FVC) as criteria for this test. The objective of the present study was to examine the extent to which these criteria were met in a community study. To do this, a random sample of 3,740 persons, aged 15 to 70 yr, of the general population of the city of Bergen and 11 surrounding municipalities on the southwest coast of Norway were enrolled in a two-phase cross-sectional study. In the second phase, a stratified sample (n = 1,512) of the respondents to the postal questionnaire used for recruitment for the study (n = 3,370) were invited to a clinical and respiratory physiologic examination that included the DLCO test. The attendance rate was 84% (1,275 of 1,512). In the examination, all subjects were able to maintain a breathholding time of 9 to 11 s, and 98% had two DLCO values within +/- 10% or 3 ml CO(STPD)/min/mm Hg of the average DLCO. The criterion of an IVC of at least 90% of FVC in the two tests was met by 68% of the subjects. Younger age was an independent predictor of failure to meet the required criteria. Thus, only two-thirds of the participants fulfilled all of the ATS criteria for the DLCO test, the main reason for failure being an IVC of less than 90% FVC. This should not necessarily lead to the exclusion from further analysis of those failing to meet this criterion.

Association of years of occupational quartz exposure with spirometric airflow limitation in Norwegian men aged 30-46 years

BACKGROUND

The association between occupational quartz exposure and ventilatory function was investigated in men in a general population after adjusting for other potential determinants of outcome.

METHODS

All eligible men aged 30-46 years living in western Norway (n = 45,380) were invited to a cross sectional community survey. This included a self administered questionnaire (with respiratory symptoms, smoking habits and occupational exposures), spirometric recordings (using dry wedge below spirometers), and a chest radiograph (65% attendance). Measurements of forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were obtained in 91% (n = 26,803) of those who participated, 26,106 of whom performed successful spirometric tests and had normal chest radiographs and remained for further analysis. Age, body mass index, and technician standardised residuals ((observed minus predicted value)/residual standard error) of maximum FEV1/height2 and FVC/height2 were used as outcome variables for adjusted lung function levels, respectively.

RESULTS

Occupational quartz exposure was reported by 13% (n = 3445) of those who participated in the survey, with a mean duration of seven years. Among those exposed to quartz, significant inverse linear relationships were observed between years of exposure and FEV1 level and the ratio of FEV1/FVC, independent of host characteristics. Multiple linear regression analyses showed that the difference in FEV1 associated with each year of quartz exposure was -4.3 ml (95% CI -1.1 to -7.5 ml; p = 0.01) compared with -6.9 ml (95% CI -4.7 to -9.1 ml; p < 0.01) from smoking 20 cigarettes/day for one year after adjusting for age, atopy, asthma, wheezing, marital status, and other occupational exposures.

CONCLUSION

In men aged 30-46 years with occupational quartz exposure and normal chest radiographs the duration of occupational quartz exposure was an independent predictor for spirometric airflow limitation.

Fish consumption and respiratory symptoms among young adults in a Norwegian community

The aim of this study was to investigate the relationship between dietary fish consumption and self-reported respiratory symptoms among young adults. A random sample of 4,300 subjects, aged 20-44 yrs, living in Bergen, Norway, received a postal questionnaire on respiratory symptoms, of whom 80% responded. Mean fish consumption was assessed in a food-frequency questionnaire by asking how often the subject consumed units of fish (150 g) during the last year. Average fish consumption was 1.8 units x week(-1). Fish intake of <1 unit x week(-1) was reported by 24%, 41% reported consumption of 1 unit x week(-1) and 35% intake of >1 unit x week(-1). A high fish intake was significantly associated with increasing age after adjusting for smoking. Adjusted for smoking habits, the prevalence of "cough at night" and "chest tightness" showed a decreasing trend with increasing fish consumption (p<0.05), while such a trend for "wheeze" was demonstrated only in smokers (p=0.008 for interaction). In logistic regression models (adjusting for age, sex, body mass, smoking habits and occupational exposure) fish consumption (three categories) was not significantly associated with "wheeze", "chest tightness", "breathless at night" or "asthma attack", although the odds ratios (OR) were consistently less than 1 (except for "asthma attack"). Fish consumption was of borderline significance as a protective factor of "cough at night", OR = 0.86 (95% confidence interval: 0.76-0.97) but in stratified analyses only in smokers. Subjects reporting very high levels of fish consumption (>14 units x week(-1)) did not have lower prevalences of respiratory symptoms. In conclusion, among young Norwegian adults, with a relatively low prevalence of asthma and an overall high fish intake, fish consumption was not a significant predictor of four out of five respiratory symptoms.

Hospitalization for lung disease in early childhood and asthma symptoms in young adulthood

Longitudinal studies have reported an association between early childhood lung disease and adult respiratory disease. This issue has not been addressed in the Nordic countries. We studied the association between hospitalization for lung disease in early childhood and asthma in young adulthood in a Norwegian population sample, while estimating the attributable fraction of childhood hospitalization. A population-based survey in Bergen, Norway included a random sample of 4300 subjects aged 20-44 years, of whom 80% responded. The effect of hospitalization for lung disease before the age of 2 years on asthma in adulthood was analysed by logistic and polytomous logistic regressions, adjusting for related variables. Adjusted attributable fractions were estimated from these models. The risk for different measures of asthma was significantly increased in the 103 persons reporting childhood hospitalization (airways symptoms: OR from 1.9 to 2.9; asthma medication: OR = 2.8). The associations with airways symptoms were stronger in women (OR from 2.6 to 5.3) than in men (OR from 1.4 to 2.4). Given a causal association, adjusted attributable fractions showed that childhood lung disease causing hospitalization explained 4% of asthma symptoms. Early childhood hospitalization for lung disease was related to asthma symptoms in young Norwegian adults, more strongly in women than in men. Only a minor proportion of asthma symptoms in this age group could be related to hospitalization for lung disease in early childhood.

Forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) variability in asymptomatic never-smoking men

We examined the effects from subjects, technicians and spirometers on within-session variability in successful recordings of forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) in 4989 asymptomatic never-smoking men. All eligible men aged 30-46 years living in western Norway (n = 45,380) were invited to a cross-sectional community survey. Information on respiratory symptoms, smoking habits and occupational exposures was obtained from a self-administered questionnaire. Three successful FEV1 and FVC recordings were obtained in 26,368 attendants using three dry-wedge bellow spirometers operated by 10 different technicians. Within-subject standard deviation (SD) from three recordings of FEV1 and FVC was on average 102 and 106 ml, respectively, and increased with height (14 and 17 ml, respectively, per 10 cm) and body mass index (BMI) (11 and 14 ml, respectively, per 5 kg m-2). Between-subject SD of the mean of three FEV1 and FVC recordings was 591 and 754 ml, respectively, and increased in groups of increasing height (43 and 40 ml, respectively, per 10 cm). Small, but significant, differences were observed between technicians in within-subject SD and in levels of FEV1 and FVC. Homogeneity of between-subject variability, necessary for linear regression analysis, was obtained using FEV1 and FVC divided by height squared. In conclusion, within-subject variability in three successful spirometric recordings was small, but dependent on height and BMI of the subjects as well as technician performance. The observed heterogeneity in between-subject variation in FEV1 and FVC levels disappeared when each variable was divided by height squared. Novel multiple linear regression equations for FEV1/height2 and FVC/height2 were developed to be used in evaluating the effects from occupational airborne exposures in Nordic men aged 30-46 years.

Invasiveness by lacZ transfected non-small-cell lung cancer cells into human bronchial tissues in vitro

To facilitate the detection of invading tumor cells in a three dimensional coculture assay in vitro, the reporter gene Escherichia coli beta-galactosidase (lacZ), was transfected into a human large-cell lung carcinoma cell line GaL23. Multicellular spheroids initiated from the transfected cell line, GaL23LZ, were confronted with fragments of human bronchial tissue differing in their surface composition. While an intact surface epithelium was found to obstruct both adhesion and invasion of tumor cells, an exposed basal lamina augmented adhesion, migration and invasion of tumor cells into the normal tissue. Tumor cells, migrating on the surface of the bronchial fragments, were found to migrate between the epithelial cells and the basal lamina. Fibroblast covered stromal fragments, derived from resected non-small cell lung cancers, were found to be more edible to the invading tumor cells than subepithelial stromal fragments from normal bronchi. The lacZ transfection made it possible to quantitatively analyze the invasive process. While the transfection neither changed the invasive ability of the tumor cells in vitro or in vivo nor their growth pattern in monolayers, three dimensional growth represented by spheroid morphology and clonogenicity in soft agar was significantly changed. This model offers an in vitro system to study qualitative and quantitative aspects of tumor-host relationships in a complex microenvironment which has several similarities to the in vivo situation.

Averaging attributable fractions in the multifactorial situation: assumptions and interpretation

In multifactorial situations, the concept of attributable fraction quantifying the population impact of exposure factors on the disease load needs special methodologic care to take the interrelationship between exposures into account. Recently, new epidemiologic parameters have been introduced to address this issue. These approaches are reconsidered here from a game-theoretical perspective. The derivation of game-theoretical properties of these parameters provides additional motivation for their use in epidemiologic practice and offers new insights into their interpretation in epidemiologic studies. The nontechnical description of the results is illustrated by examples from the Hordaland study on obstructive lung disease.