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Biomedical subjects

P Magnus

Publications and source records attributed to P Magnus.

At least 73 records · Page 4Linked to original sources
PubMed1998

A rare CYP19 (aromatase) variant may increase the risk of breast cancer.

The aromatase P450 (coded by the CYP19 gene) is responsible for the rate limiting step in the metabolism of C19 steroids to estrogens and is expressed in most breast carcinomas. A polymorphic tetranucleotide repeat (TTTA)n in intron 5, about 80 nucleotides downstream of exon 4 has previously been described. The allele frequencies of the polymorphic repeat were studied in series of 182 sporadic and 185 familial breast cancer patients as well as in 252 healthy control individuals. Five different alleles containing 7, 8, 9, 11 and 12-TTTA-repeats were detected. A relatively rare allele (A1) containing the longest repeat (TTTA)12 was found significantly more frequently in breast cancer patients than in control individuals. This indicates that individuals carrying the A1 allele of CYP19 may have an increased risk of developing breast cancer, OR 2.42 (95% confidence interval [CI] 1.03-5.80). The higher frequency was observed in both sporadic and familial patients, although when each of the groups was compared to the control group only a borderline significance was seen. A higher frequency of A1 allele carriers was also found in the group of patients with positive estrogen receptor and progesterone receptor positive tumors. These data suggest that the CYP19 gene may be involved as a low penetrance gene in breast cancer susceptibility.

Adult↗
PubMed1998

Recurrent respiratory tract infections during the first 3 years of life and atopy at school age.

BACKGROUND: The hypothesis that infections reduce the risk of atopy was investigated by estimating the association between recurrent respiratory tract infections during the first 3 years of life and atopy at school age. METHODS: According to surveys in three different areas of Norway, children were classified into three groups: asthma, wheeze without asthma (wheeze), and no asthma/no wheeze. The skin prick test (SPT) was conducted on a stratified random sample of children (n = 502). The outcome was at least one positive SPT. The exposure variable was retrospective parental report of respiratory tract infections during the first 3 years of life. RESULTS: Infections were negatively associated with atopy, crude odds ratio (cOR) = 0.3, 95% confidence interval (95% CI) 0.1-0.7, in the asthma group. A similar association was present in children with wheeze cOR = 0.4 (95% CI 0.1-1.2). The number of siblings was not associated with atopy in any group. Infections remained negatively associated with atopy in children with asthma, aOR = 0.3 (95% CI 0.1-0.7), in a logistic regression model adjusting for confounding factors. A similar pattern was present in the wheeze group. CONCLUSIONS: Recurrent respiratory tract infections during the first 3 years of life are negatively associated with atopy at school age in children with asthma.

Adolescent↗
PubMed1998

Herpes simplex virus and human papillomavirus in a population-based case-control study of cervical intraepithelial neoplasia grade II-III.

In order to evaluate the association between seropositivity for herpes simplex virus (type 1 and type 2) and cervical intraepithelial neoplacia (CIN), we analysed data from a population-based case-control study of CIN grade II-III which included Norwegian women aged 20 to 44 years, 94 cases and 228 controls. Our objectives were to determine if HSV-1 and/or HSV-2 seropositivity were independent risk factors for CIN, taking human papillomavirus exposure into account, and to elucidate the combined effect of HPV positivity and seropositivity for HSV In logistic regression analyses, the association between HSV-2 or HSV-1 seropositivity and CIN II-III was not explained by HPV (adjusted OR 3.0; 95%, CI 1.3-7.2 and adjusted OR 3.3; 95% CI 1.3-8.4, respectively). In analyses restricted to HPV-16 DNA-positive individuals, seropositivity for HSV-2 increased the risk of CIN (OR 11.1; 95% CI 1.2-105.7), whereas HSV-1 seropositivity was not significantly associated with CIN. In women positive for other HPV types, only HSV-1 seropositivity was associated with CIN (OR 8.5; 95% CI 1.3-55.8). In analyses of the HPV-16-seropositive individuals, neither HSV-1 nor HSV-2 seropositivity was associated with CIN. Compared to the reference group of jointly unexposed subjects, the HPV-16 DNA-positive women who were anti-HSV-2 negative had an increased risk of CIN (OR 29; 95% CI 12-67), whereas the risk in women who were both HPV-16 DNA-positive and HSV-2 was OR=247 (95% CI 31-1996). The estimate of interaction was strong, but did not reach significance, and our findings may suggest that the combined effect of the two viruses is of aetiological importance in cervical carcinogenesis. Furthermore, the results indicate that HPV DNA positivity is not sufficient to explain the sexual behaviour-associated risk of cervical neoplasia and that further studies on the role of genital HSV (type 1 as well as type 2) and other STDs are warranted.

Antibodies, Viral↗
PubMed1998

Residential dampness problems and symptoms and signs of bronchial obstruction in young Norwegian children.

To assess the role of dampness problems and house dust mite exposure in the development of bronchial obstruction in early life, a cohort of 3,754 children born in Oslo during 1992 and 1993 was followed for 2 yr. Bronchial obstruction was defined as two or more episodes with symptoms and signs of obstruction or one lasting 1 mo or more. A matched case-control study was carried out in 251 cases of bronchial obstruction (response rate: 98%) and their 251 paired controls. Information on home dampness problem(s), house dust mite exposure, and potential confounders was collected during home visits and by questionnaires. Dampness problems were confirmed in the homes of 27% of the cases and 14% of the controls, while a concentration of Dermatophagoides pteronyssinus allergens > 2 microg/g dust was found in the beds of 11 (4.5%) cases and three (1.2%) controls. In conditional logistic regression analysis controlling for potential confounders, confirmed dampness problems increased the risk of bronchial obstruction (adjusted odds ratio: 3.8; 95% confidence interval: 2.0-7.2). Exposure to D. pteronyssinus allergens > 2 microg/g dust increased the risk of bronchial obstruction (adjusted odds ratio: 2.8; 95% confidence interval: 0.7-11.7). Residential dampness problems in Oslo dwellings seem to increase symptoms and signs of bronchial obstruction in young children, apparently without increasing their exposure to house dust mites.

Airway Obstruction↗
PubMed1998

Nicotine concentration in the hair of nonsmoking mothers and size of offspring.

OBJECTIVES: The purpose of this study was to estimate the risk of small-for-gestational-age birth by levels of nicotine in the hair of mothers and offspring. METHODS: In a sample of 58 case subjects and 105 control subjects, hair nicotine concentrations were measured by gas chromatography and mass spectrometry. RESULTS: With women whose hair nicotine concentrations were in the lowest quartile as the reference group, the odds ratio (OR) for small-for-gestational-age birth was increased among women with concentrations in the upper and two middle quartiles (OR=4.2, 95% confidence interval [CI]=1.5, 11.5, and OR = 3.2, 95% CI=1.3, 8.0). When smoking mothers were excluded from the analysis, the corresponding odds ratios were 2.1 (95% CI=0.4, 10.1) and 3.4 (95 % CI= 1.3, 8.6). CONCLUSIONS: The results suggest that passive maternal smoking increases the risk of small-for-gestational-age births.

Case-Control Studies↗
PubMed1998

Determinants of asthma in a farming population.

OBJECTIVES: This study examined the determinants of asthma in a population of farmers, including as a crude indicator of genetic predisposition "history of asthma in next-of-kin" (family history), and exposure factors such as animal production and smoking. METHODS: In a cross-sectional study of 8482 farmers or farmers' spouses in Norway a questionnaire with information on asthma among the subjects and their next-of-kin, production type and farming activities, exposures outside farming, and smoking was applied. Spirometry was performed. RESULTS: The lifetime prevalence of self-reported asthma in the population was 6.3%. Significant risk factors for current asthma were asthma among next-of-kin, asthma as child or adolescent, animal production, and age. In a comparison with subjects with no family history of asthma and no animal production the adjusted odds ratio for current asthma in never smokers was 1.9 [95% confidence interval (95% CI) 0.4-8.9] for subjects with family history only, 2.2 (95% CI 1.1-4.2) for subjects with animal production only, and 6.3 (95% CI 3.1-13.1) for subjects with both factors. A combination of animal production, smoking, and a positive family history gave an odds ratio of 8.1 (95% CI 4.0-16.2) for current asthma. CONCLUSIONS: The study can be interpreted as support for the hypothesis of an interaction between genetic factors and exposure factors in the causation of asthma. Since familial associations may be exposure-related, the necessity of considering indicators of both inheritance and exposure in epidemiologic studies of asthma is emphasized.

Adult↗
PubMed1998

Combined effect of smoking and human papillomavirus type 16 infection in cervical carcinogenesis.

To study the combined effect of smoking and human papillomavirus (HPV) type 16 infection in high-grade cervical intraepithelial neoplasia, we analyzed data from a Norwegian population-based case-control study including 90 patients and 216 controls, 20-44 years of age. We assessed HPV-16 status both by polymerase chain reaction detecting virus DNA and by enzyme-linked immunosorbent assay detecting antibodies against virus capsid. Smoking was associated with cervical intraepithelial neoplasia grade II-III in HPV-16-positive individuals. Using the jointly unexposed (HPV-16 DNA-negative never-smokers) as the reference group, we determined the risk of cervical intraepithelial neoplasia grade II-III in HPV-16 DNA-positive never-smokers and HPV-16 DNA-positive ever-smokers (odds ratio = 15.7; 95% confidence limits = 3.2, 76.5, and odds ratio = 65.9; 95% confidence limits = 22.3, 194.3, respectively). The estimated proportion of cases among HPV-16-positive smokers that is attributable to the interaction between the two causes is 74%, based on HPV-16 DNA positivity.

Adult↗
PubMed1997

Secular trend in the occurrence of asthma among children and young adults: critical appraisal of repeated cross sectional surveys.

OBJECTIVES: To review repeated surveys of the rising prevalence of obstructive lung disease among children and young adults and determine whether systematic biases may explain the observed trends. DESIGN: Review of published reports of repeated cross sectional surveys of asthma and wheezing among children and young adults. The repeated surveys used the same sampling frame, the same definition of outcome variables, and equivalent data collection methods. SETTING: Repeated surveys conducted anywhere in the world. SUBJECTS: All repeated surveys whose last set of results were published in 1983 or later. MAIN OUTCOME MEASURES: Lifetime and current prevalences of asthma and current prevalence of wheezing. The absolute increase (yearly percentage) in the prevalences of asthma and wheezing was calculated and compared between studies. RESULTS: 16 repeated surveys fulfilled the inclusion criteria. 12 reported increases in the current prevalence of asthma (from 0.09% to 0.97% a year) and eight reported increases in the current prevalence of wheezing (from 0.14% to 1.24% a year). Changes in labelling are likely to have occurred for the reporting of asthma, and information biases may have occurred for the reporting of wheezing. Only one study reported an increase in an objective measurement. CONCLUSIONS: The evidence for increased prevalences of asthma and wheezing is weak because the measures used are susceptible to systematic errors. Until repeated surveys incorporating more objective data are available no firm conclusions about increases in obstructive lung disease among children and young adults can be drawn.

Adolescent↗
PubMed1997

Mothers' birth weight and survival of their offspring: population based study.

OBJECTIVE: To test the hypothesis that a baby's survival is related to the mother's birth weight. DESIGN: Population based dataset for two generations. SETTING: Population registry in Norway. SUBJECTS: All birth records for women born in Norway since 1967 were linked to births during 1981-94, thereby forming 105104 mother-offspring units. MAIN OUTCOME MEASURES: Perinatal mortality specific for weight for offspring in groups of maternal birth weight (with 500 g categories in both). RESULTS: A mother's birth weight was strongly associated with the weight of her baby. Maternal birth weight was associated with perinatal survival of her baby only for mothers with birth weights under 2000 g. These mothers were more likely to lose a baby in the perinatal period (odds ratio 2.3, 95% confidence interval 1.4 to 3.7). Among mothers with a birth weight over 2000 g there was no overall association between mother's weight and infant survival. There was, however, a strong interaction between mother's birth weight, infant birth weight, and infant survival. Mortality among small babies was much higher for those whose mothers had been large at birth. For example, babies weighing 2500-2999 g had a threefold higher mortality if their mother's birth weight had been high (> or = 4000 g) than if the mother had been small (2500-2999 g). CONCLUSION: Mothers who weighed less than 2000 g at birth have a higher risk of losing their own babies. For mothers who weighed > or = 2000 g their birth weight provides a benchmark for judging the growth of their offspring. Babies who are small relative to their mother's birth weight are at increased risk of mortality.

Adolescent↗
PubMed1997

Frequency of sexual partner change in a Norwegian population. Data distribution and covariates.

The number of new sexual partners per year (partner frequency) is a key factor in the spread of sexually transmitted diseases. Data from two Norwegian population-based surveys conducted in 1987 and 1992 were used to estimate recent (in the previous 3 years) and earlier partner frequency and to examine covariates affecting the distribution of partner frequency. Seventy-two percent of respondents reported having no new partners per year, and 2% reported having more than three new partners per year. Results from a Poisson regression model indicated that a low partner frequency was associated with being married or cohabiting, being female, greater age, and late sexual debut. Partner frequency was lower in 1992 than in 1987 (rate ratio = 0.8, 95% confidence interval 0.7-0.9). In comparison with earlier life, there was a large reduction in partner frequency for married/cohabiting individuals. In contrast, there was either no change or some increase in partner frequency for single persons.

Adolescent↗
PubMed1997

Effect of changing partnership formation rates on the spread of sexually transmitted diseases and human immunodeficiency virus.

Core population groups play an important role in the spread of sexually transmitted diseases. Subjects in a core group may change their behavior over time and "migrate" to the noncore. The authors examined the effects of such migration on the prevalence of gonorrhea, chlamydia, and human immunodeficiency virus (HIV) using a mathematical model. The size of the core and the migration rate from the core to the noncore were estimated from population-based sexual survey data on 8,445 Norwegians collected in 1987 and 1992. Sixty-four percent of the sample was considered without risk of contracting a sexually transmitted disease. The core group made up 2.5% of the remaining sample. The migration rate from the core was estimated at 12% per year. The three types of infections analyzed exemplify three different patterns of the effect of migration on infection prevalence in the core/noncore groups: gonorrhea = no effect/no effect, Chlamydia = no effect/increase, and HIV = decrease/increase. Migration affects the basic reproductive ratio of diseases with a long infectious period more than that of diseases with a short infectious period. For HIV, this means that the later stages of infection contribute less to the basic reproductive ratio in the presence of migration. The results are qualitative and show that detailed knowledge about mixing, migration, transmission rates, and duration of infectiousness is necessary to make accurate predictions.

Adolescent↗
PubMed1997

Birth defects and parental consanguinity in Norway.

The study compares frequencies of birth defects between immigrant groups and the rest of the Norwegian population in Norway and estimates the influence of consanguinity and socioeconomic factors on these frequencies. The authors studied all 1.56 million births in Norway from 1967 to 1993. Of these, 7,494 children had two Pakistani parents, 84,688 had one Norwegian and one immigrant parent, and 25,891 had two immigrant parents from countries other than Pakistan. The risk of birth defects relative to the Norwegian group was 0.98 (95% confidence interval 0.92-1.03) in the group with one foreign and one Norwegian parent, 1.39 (95% confidence interval 1.22-1.60) in the group with two Pakistani parents, and 1.04 (95% confidence interval 0.95-1.14) in the group with two parents from other foreign countries; 0.1% of the Norwegian and 30.1% of the Pakistani children had parents who were first cousins. There was no difference in risk between children of nonconsanguineous Pakistani parents and the other groups. The relative risk of birth defects among children whose parents were first cousins was about 2 in all groups. Among the Pakistani, 28% of all birth defects could be attributed to consanguinity. Low paternal educational level was associated with a slightly increased risk in the Norwegian group, while independent effects of parental educational levels were not found in any other groups.

Confidence Intervals↗
PubMed1997

[Occurrence of asthma among school children in Norway during the period 1985-94].

Several comparable surveys of childhood as have been performed in Norway. This article describes the prevalence among children, 6-13 years old, during the period 1985-94, and how this prevalence is influenced by the operational definition of asthma. Questionnaires were administered in eight areas; Troms/Finnmark (1985), Nordland (1985), Ardal/Laerdal (1989/92), Sør-Varanger (1992), Oslo (1994), Hallingdal (1994) and Odda (1994). The response rates varied from 85 to 96%. The parent-reported lifetime prevalences were lowest in the areas where the studies took place in 1985, the earliest year of study; Nordland 7.2% (95% CI 6.5-7.9), Troms/Finnmark 8.1% (7.4-8.8). The prevalence increased up to 1994, with the highest prevalence in Oslo 13.7% (12.0-15.4). The prevalence of current asthma was about half the lifetime prevalence; Oslo 5.7% (4.6-6.8) compared with 10.1% (8.5-11.6). When respiratory symptoms the estimates were doubled in some areas and regional differences were reduced. The prevalence increased during the study period and seemed to be highest in northern Norway. Regions classified as polluted did not have a higher prevalence.

Adolescent↗
PubMed1997

Perinatal outcome after leave of absence from work for twin-pregnant women.

AIM: To evaluate the association between the incidence of leave of absence from work and perinatal outcome for the twin-pregnant woman. MATERIAL AND METHODS: A 20.2% sample of all twin-pregnant women between 1982 and 1988 (1,331/6,602) was taken at random from the entire material of twin deliveries in Sweden, archived at the Medical Birth Registry (MBR), National Board of Health and Welfare. For each woman in the sample, information on period(s) and reasons for leave of absence from work during pregnancy was obtained by inquiry to all Regional Health Insurance Offices throughout Sweden. A comparison of perinatal outcome was also made with information from the Danish Fertility Database and the Norwegian Medical Birth Registry. RESULTS: Duration of leave from work increased from 58 days in 1982 to 97 days in 1988 (trend analysis; t = 7.9, p < 0.001). No association was seen between perinatal mortality for twins weighing < 1,500 g and changes in the incidence of leave of absence. The incidence of twins with a birthweight < 1,500 g varied among the three countries, increasing significantly only in Sweden (trend analysis chi 2 = 20.3, p < 0.0001). CONCLUSION: Although the number of days of leave of absence increased by 60%, there was no obvious association with perinatal mortality for twins weighing < 1,500 g. The incidence of Swedish twins with a birthweight < 1,500 g increased significantly, indicating that the effect of leave of absence from work on perinatal outcome may be less effective than previously thought.

Female↗
PubMed1997

Genetic and environmental contributions to the correlation between alcohol consumption and symptoms of anxiety and depression. Results from a bivariate analysis of Norwegian twin data.

Two thousand five hundred seventy pairs of Norwegian MZ and like-sexed and unlike-sexed DZ twins aged 18-25 years completed questionnaires with information about symptoms of anxiety and depression and alcohol consumption. The aim of the study was to estimate sex-specific genetic and environmental effects unique to symptoms of anxiety/depression and to alcohol consumption and effects common to the two phenotypes. Five models fitted the data almost equally well. The heritability estimate from these models ranged from .23 to .57 for male alcohol consumption, from .39 to .59 for female alcohol consumption, from .25 to .48 for male anxiety/depression, and from .45 to .56 for female anxiety/depression. The phenotypic correlation between alcohol and anxiety/depression in males (r = .23) could be fully explained by common genetic effects. The correlation in females (r = .18) was caused by individual environmental factors together with either genetic effects or family environment.

Adolescent↗
PubMed1997

The relationship between maternal birthweight and gestational age in twins and singletons and those of their offspring in Norway.

In order to elucidate whether maternal plurality affects offspring intrauterine growth, the relationship between birthweight and gestational age of twins and singletons and those of their first singleton liveborn children in Norway was studied using data from the Medical Birth Registry. The population-based sample consisted of 49,698 mother-offspring pairs (48,842 with singleton and 856 with twin-mothers). In bivariate analyses, no significant differences in mean birthweight and gestational age of offspring of twin and singleton mothers were found, although the mean birthweight and gestational age of the twin-mothers themselves were significantly lower than those of singletons (819 g and 14 days respectively). In multiple regression analysis, the expected birthweight of offspring was 230.3 g (95% CI: 193.2-267.4 g) higher when the mother was a twin than when the mother was a singleton, when controlling for non-standardised maternal birthweight. When adjusting for relative maternal birthweight (z-score), the association between maternal plurality and offspring birthweight was not statistically significant. The results suggest that being born as a twin has no substantial consequences on offspring growth in utero and show that mean differences in birthweight between twins and singletons should be standardised when both groups are included in multivariate studies.

Birth Weight↗
PubMed1997

A risk index for sexually transmitted diseases.

BACKGROUND AND OBJECTIVES: The basic reproductive ratio, RO, is a useful measure to compare the potential for spread of sexually transmitted diseases (STDs) between populations. But RO is a population risk measure; and individual risk index is needed. STUDY DESIGN: An individual, STD-specific potential risk index was developed based on the basic reproductive ratio formula. The index was estimated for 10,643 subjects aged 18 to 60 years taking part in surveys of sexual behavior conducted in 1987 and 1992, using human immunodeficiency virus (HIV) and chlamydial infections as examples. RESULTS: Of the total population, 2.8% were at potential risk for HIV infection, and 5.2% for chlamydial infection. The two groups overlapped only partially. There where more than 15 times as many at potential risk among single subjects as among married/cohabiting subjects for both infections. CONCLUSIONS: The risk index developed measures STD-specific potential risk. It can be used to estimate the size of risk groups in populations, and the association between risk and sociodemographic and behavioral variables. Further research is needed to include the effects of partner mixing in the index.

Adolescent↗