Rehospitalization for respiratory syncytial virus infection in infants with extremely low gestational age or birthweight in Denmark.

AIM: To determine the risk of rehospitalization for respiratory syncytial virus (RSV) infection during the first 2 y of life in extremely preterm infants. METHODS: Records on all rehospitalizations during the first 2 living years of all infants born with gestational age <28 wk or birthweight <1,000g during 1994 and 1995 in Denmark were retrospectively reviewed. RESULTS: Among 240 eligible infants, 43 (18%) had been rehospitalized 48 times owing to RSV. In infants (n = 210) without CLD the risk of rehospitalization for RSV was 16%, whereas in infants with CLD (n = 30) it was 30% (p = 0.065). Eighteen infants (38%) required respiratory support (supplemental oxygen only 3, continuous positive airway pressure 14, mechanical ventilation 1). Apart from CLD the only factor that could be associated with increased risk of hospitalization for RSV was discharge during autumn (p = 0.05). No infant died from RSV infection. CONCLUSION: The high rate of rehospitalization for RSV in extremely preterm infants in Denmark, especially in infants with CLD, should lead to considerations concerning more widespread use of prophylaxis against RSV in these infants.

IgE in unselected like-sexed monozygotic and dizygotic twins at birth and at 6 to 9 years of age: high but dissimilar genetic influence on IgE levels.

BACKGROUND: IgE is a major determinant of allergic disease. Twin analysis of serum levels of IgE has been carried out previously in children and adults with heritability estimates of 30% to 70% on the basis of ANOVA. OBJECTIVE: This study included the analysis of serum IgE in a population of 126 twins, 27 monozygotic pairs and 36 dizygotic pairs, studied at birth (cord blood [CB] IgE) and consecutively at the age of 6 to 9 years of age (serum IgE). METHODS: IgE was determined by means of RIA. ANOVA, correlation analysis, and structural equation modeling by maximal likelihood analysis was used for genetic analysis. RESULTS: Structural equation modeling by maximal likelihood analysis showed the best-fitting model to be the AE model (A for additive genetic variance and E for environmental variance) both at birth and later in childhood. The estimated heritability was 0.92 (95% CI, 0.84-0.95) for CB IgE and 0.78 (95% CI, 0.60-0.87) for serum IgE. The correlation between CB IgE and serum IgE was 0.04. CONCLUSIONS: The study demonstrated a higher genetic dependency of serum IgE than previously recognized. The low correlation between the IgE levels at birth and later in childhood suggested that different effector mechanisms may be operating at different ages.

Untangling genetic influences on smoking, body mass index and longevity: a multivariate study of 2464 Danish twins followed for 28 years.

A multivariate twin study was conducted in order to evaluate to what extent smoking, BMI and longevity are influenced by common genetic factors. The study was based on a 28-year follow-up of a sample of 2464 Danish twins who were born in the period 1890-1920 and who answered a questionnaire, including requests for information on smoking status, height and weight, in 1966. By 1994, approximately 2/3 of the sample had died. To compensate for the right-censoring, age at death was imputed for twins who were still alive by using survival analysis; all living subjects were more than 73 years old (mean 80 years, SD 5) in 1994. Proportions of covariance resulting from genetic and environmental factors in common and unique to the three traits were estimated from covariance matrices using the structural equation model approach. The study found no evidence for a substantial impact of common genetic factors on smoking, BMI and longevity. This suggests that only a small fraction of the genetic influences on longevity is mediated via a genetic influence on smoking and BMI and, furthermore, that it is unlikely that the associations between smoking and mortality and between BMI and mortality are confounded by common genetic factors.

The heritability of human longevity: a population-based study of 2872 Danish twin pairs born 1870-1900.

The aim of this study was to explore, in a large and non-censored twin cohort, the nature (i.e., additive versus non-additive) and magnitude (i.e., heritability) of genetic influences on inter-individual differences in human longevity. The sample comprised all identified and traced non-emigrant like-sex twin pairs born in Denmark during the period 1870-1900 with a zygosity diagnosis and both members of the pairs surviving the age of 15 years. A total of 2872 pairs were included. Age at death was obtained from the Danish Central Person Register, the Danish Cause-of-Death Register and various other registers. The sample was almost non-censored on the date of the last follow-up (May 1, 1994), all but 0.6% had died, leaving a total of 2872 pairs for analysis. Proportions of variance attributable to genetic and environmental factors were assessed from variance-covariance matrices using the structural equation model approach. The most parsimonious explanation of the data was provided by a model that included genetic dominance (non-additive genetic effects caused by interaction within gene loci) and non-shared environmental factors (environmental factors that are individual-specific and not shared in a family). The heritability of longevity was estimated to be 0.26 for males and 0.23 for females. The small sex-difference was caused by a greater impact of non-shared environmental factors in the females. Heritability was found to be constant over the three 10-year birth cohorts included. Thus, longevity seems to be only moderately heritable. The nature of genetic influences on longevity is probably non-additive and environmental influences non-shared. There is no evidence for an impact of shared (family) environment.

Sex and age specific assessment of genetic and environmental influences on body mass index in twins.

OBJECTIVE: To assess, by use of a population based twin register, if there are sex and age differences in genetic and environmental influences on inter-individual variation in BMI among middle-aged and elderly subjects. DESIGN: Twin study. SUBJECTS: 1233 like-sex Danish twin pairs (213 MZ male, 322 DZ male, 280 MZ female, 418 DZ female pairs, age: 46-76 years, BMI: 15-45 kg/m2). MEASUREMENTS: Self-reported height and weight. METHODS: Proportions of variance due to genetic and environmental factors were estimated from variance-covariance matrices using the structural equation model approach. RESULTS: The most parsimonious explanation of the data was provided by a model that included additive genetic and non-shared environmental factors with the latter fixed to be equal across sex and age. The heritability of BMI was estimated to be 0.46 for males aged 46-59 years, 0.61 for males aged 60-76 years, 0.77 for females aged 46-59 years and 0.75 for females aged 60-76 years. CONCLUSION: As in earlier studies, the present one showed a high heritability of BMI throughout adult life, with genetic influences being mainly additive and environmental influences being non-shared, without evidence for major impact of genetic dominance or shared environment. Most twin, family and adoption studies do not suggest important sex or age differences in magnitude of genetic effects, but we found that females had greater heritability than males, and that heritability in males increased by age.

[Antiphospholipid antibodies and occlusive vascular disease]. / Anti-fosfolipidantistoffer og okklusiv karsygdom.

The antiphospholipid syndrome is characterized by venous and/or arterial thrombosis, recurrent foetal loss, thrombocytopenia and the presence of antiphospholipid antibodies. This study presents three case reports, which emphasize the multiform clinical features of the syndrome: one case of uncomplicated myocardial infarction in childhood and two prolonged, clinically elusive case histories, both with fatal outcome due to acute, multifocal, non-inflammatory vascular occlusion. It is important to distinguish between this syndrome and various vasculitis syndromes, although consensus on therapy for the antiphospholipid syndrome has not yet been achieved.

Is standard 555 MBq 131I-therapy of hyperthyroidism ablative?

The effect of a standard 555 MBq 131I dose in ablating the thyroid gland was investigated in 116 consecutive hyperthyroid patients. Fifty-one had Graves' disease, 50 a multinodular toxic goitre and 15 had a solitary toxic nodule. 555 MBq 131I was given regardless of size or type of the gland and severity of the disease. Within one year after this dose hypothyroidism was induced in 41% of patients with Graves' disease, but in only 13% with a solitary toxic adenoma, and 6% with a multinodular gland. Forty-eight percent of the patients with a multinodular gland, 33% with Graves' disease and 13% with a solitary toxic nodule were still hyperthyroid. Since this so called ablative treatment only accomplishes hypothyroidism in 26/116 (23%) of our patients and results seem unpredictable 131I treatment adjusted according to gland size and type aiming at achieving euthyroidism could be contemplated.

[Indicators of coronary risks--attitude, knowledge and behavior. An interview study among 917 men and women aged 25-44 years]. / Koronare risikoindikatorer--holdning, viden og adfaerd. En interviewundersøgelse blandt 917 maend og kvinder i alderen 25-44 år.

The purpose of this study was to clarify whether there was any agreement between knowledge about coronary risk factors, attitudes to individual prevention of coronary heart disease and preventive health behaviour. In particular the differences between males and females were examined. A total of 749 persons ranging in age between 25 and 44 (that is 82% of a random group of 917 persons) were interviewed in this cross sectional study. Physical inactivity, smoking and fat consumption were used as behaviour related risk factors. Generally, young adult Danes had a poor knowledge and poor health behaviour related to coronary heart disease in spite of their positive attitudes towards prevention. The study indicated that neither attitudes nor knowledge were correlated to preventive health behaviour. Women had better health behaviour patterns than men despite the same amount of knowledge and attitudes. In the above mentioned connexions, men showed positive correlation while no correlation existed for women.